The invention relates to an electronic key.
Electronic keys serve for actuating a locking system. This may be, in particular, a door locking and/or ignition lock system on an automobile.
An electronic key of this type is known from German Patent Document No. DE-A-195 05 190. The electronic key possesses means for the intended operation, such as a transmitter and, if appropriate, a receiver. With the aid of these means, at least one coded operating signal can be transmitted between the electronic key and the locking system. If the subsequent evaluation of the transmitted operating signal is positive, meaning that the electronic key belonging to the locking system is being used, corresponding functions of the locking system are actuated. These functions may be access authorization by virtue of the locking or unlocking of the automobile doors or an immobilization by virtue of the releasing of the engine control via the ignition lock or the like.
Modern electronic keys use, for the operating signal, high-level codes, for example a hash code, which are secure and insurmountable. If the key is misappropriated, however, the automobile can nevertheless be stolen. So-called xe2x80x9ccarjackingxe2x80x9d, in which the automobile together with the associated key is taken away from the driver by force, is also increasingly occurring. Costly antitheft systems therefore additionally use a satellite-assisted GPS (Global Position System) system with a telephone connection from the automobile to a control center, so that, under certain circumstances, the stolen vehicle can thereby be located after the theft.
An object of which the invention is to develop further the known electronic key, in such a way that the actuation of the locking system can be prevented, even without costly additional systems, if the associated key is misappropriated.
In the invention, the key can be programmed with an additional individual code. The key can be put into an activated state, in which the intended use of the key is blocked. A misappropriated key consequently cannot be used by the thief. Only if the correct individual code is entered does the key then change over again to the inactivated state, in which the key can be used as intended.
The programming of a new individual code can be carried out during the transition from the inactivated to the activated state. Likewise, during this transition, the reactivation of an already programmed individual code may also take place. The individual code is entered by means of the actuating members located on the housing of the key and serving for triggering the transmission of the coded operating signal, for example by means of the locking button for locking the automobile doors, the opening button for unlocking the automobile doors and the trunk button for opening the trunk lid. At the same time, in the case of individual code consisting of a numeric code, the actuating members are assigned corresponding digits in the numeric code and the number of actuations of the associated actuating member codes the respective digit. Expediently, a delay time is provided for clearing the actuating members in order to enter the individual code after the command to change over between the activated and inactivated state has been triggered, and the expiry of the delay time may be indicated, for example by a lighting means on the housing of the key.
The changeover between the activated and inactivated state may be triggerable by means of one of the actuating members, preferably the locking button being used to change over to the activated state and the opening button being used to change over to the inactivated state. An additional actuating member, in particular a button, for triggering the command to change over between the activated and inactivated state may likewise be arranged on the housing.
The reactivation of an already programmed individual code may likewise be carried out by the repeated interrupted actuation of the one of the actuation members, for example by pressing the locking button three separate times. When the automobile is in the driving mode, reactivation may also be carried out by the protracted actuation of any desired actuating member, so that the key, after being extracted from the ignition lock, cannot be used without knowledge of the individual code. If an automobile which has stopped is attacked, the thief then only takes away an automobile which can subsequently no longer be put into operation. In order to prevent the individual code from being discovered by trial and error, an antiplay device may be provided by a permanent changeover to the activated state, with the coded operating signal being blocked, when the wrong individual code is entered several times. It is then possible for the blocked state to be deactivated only in the workshop by resetting the key by means of a special code which is related to the respective key or the automobile.
The key may possess an indicator in order to display the changeover to the activated and/or inactivated state. This indicator may take the form, for example, of a lighting means flashing for a specific timespan at high frequency on the housing of the key, flashing taking place when an actuating member on the key is actuated in the activated state. It is likewise possible that, when the actuating member is actuated, a light emitting diode on the housing lights up red in the activated state of the key and green in the inactivated state. The battery check light on the housing of the key may be used, for example, as the lighting means. Of course, not only the state just assumed in each case by the key may be indicated, but also the transition per se between the activated and inactivated state.
In a particular development, the key can be changed over to a cleared state, in which the transmission of the coded operating signal is released only for a limited period of time, up to a specific date, for a limited number of starting operations in the ignition lock or the like. After the period of time has elapsed, after the date has been reached, after the number of starting operations has been exhausted or the like, the key then changes over to the activated state automatically. Preferably, the programming of the data for the cleared state takes placed in the inactivated state, and, once again, the actuating members on the key may be used for entering the data. To determine to what extent the limited period of time has elapsed or the date for clearance has been reached, the key may possess a realtime clock.
As an aid for the user during programming of the key, it is appropriate to arrange on the housing an indicator, such as a display, light emitting diodes or the like, for displaying the entry of the individual code or the entry of the data for the cleared state. An indicator already located in the automobile, such as a display on the steering wheel, the instrument cluster in the instrument panel or the like, may also be used for this purpose, in which case the key is inserted into the ignition lock of the automobile in order to program the individual code or to program for clearance. With the aid of an indicator of this type in the automobile, guidance for the operator to enter data during programming can be achieved in a particularly simple way. If appropriate, actuating members assigned to the indicator may then also be used for entry, instead of the actuating members located on the housing of the key.
It is appropriate, furthermore, if required, to output on the indicator the other data stored in the key, in particular the remaining period of time or the remaining number of starting operations in the cleared state, the time of the realtime clock in the key, etc. Expediently, the realtime clock can be set via the indicator and transfer of the clock time of the instrument cluster into the key can be made possible during the changeover to the cleared state. Furthermore, the mode of the key, that is to say whether it is in the inactivated or activated state, may also be output on this indicator in the automobile.
When the key is in the ignition lock, the charge state of a battery serving for the intended operation of the key and located in the housing may be output at the same time in this indicator for checking purposes. If the charge state falls short of a certain limit, the user""s attention is drawn to this by an alarm function. The charge state may also be output in this indicator for after battery-operated devices, for example for a mobile phone.
An advantage of the invention is that the user can secure the key individually against unauthorized use in a simple way. This individual securing comprises a simple additional programming of the key with a multidigit, in particular 2- or 3-digit individual numeric code or a language code. It is especially advantageous that this securing by programming the key may take place only in areas which are at risk, such as, for example, in a hotel, restaurant or the like, whilst the key may otherwise be used in the conventional way without this individual securing.
Even during travel, when the key is located in the ignition lock of the automobile, programming already used once may be activated again. This can take place in a simple way, for example, as a result of the protracted pressing of one of the actuating members on the key. So called xe2x80x9ccarjackingxe2x80x9d can thereby be effectively prevented without any safety risk for the driver, since the thief subsequently finds that he can no longer use the key.
The key having the security function according to the invention is simple to handle. Thus, the buttons already present on the key may also be used for programming or activating and for cancelling or over-writing or for deactivating the individual coding. It is also possible to reuse or reactivate the already selected programming for the individual code by the repeated protracted pressing of an actuating member, for example by pressing the locking button 3 times.
It is also especially advantageous to use a display which is already present in the automobile, and which may be located, for example, in the instrument cluster, in order to indicate the data stored in the key, relating to the vehicle and driver and to the state of the key. User guidance for programming the key may also be provided on the display. In addition, the battery charge state of the key, said state being determined via an automatic test, may be indicated on the display. The ergonomics for the key can be enhanced even further thereby.
Since these additional functions for the key can also be performed by software, there is then no need for any additional parts on the key. A great increase in security at little extra cost is thus possible. Nonrecurring extra costs are incurred only in respect of a somewhat increased outlay in terms of software in the design or development phase, if the memory of the microcontroller in the key is not yet fully occupied.
An exemplary embodiment of the invention, along with various developments, is illustrated in the drawings and is described in more detail below.